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Comment by PaulDavisThe1st | Hacker News Reader

There is nowhere that renewables are remotely close to working "nearly alone" if you are talking about total energy needs (which MacKay is/was).

There's some incredible progress for electricity generation, but there's still huge amounts of energy being used in ways that are not currently electrified and not close to electrifiable in the short term.

We should celebrate the forward progress, but also not be blind to what is not yet feasible (while also hoping that it may soon be so).

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You're right, and I appreciate the correction — even Norway mostly runs its transport on fossil fuels, not electricity, and trucking and ships aren't going to be electrifiable in the short term. Here in Argentina, when we ran our grid mostly on hydroelectric, the cars were still running mostly on gasoline and compressed natural gas.

(Yes, I know that makes me sound like an LLM.)

Right, as long as you specify “without energy storage”, renewables “can’t work alone,” even though energy storage is included in most common sense definitions of “renewables”

Thankfully, energy storage is being deployed worldwide, so this is a moot point, and renewables can and will replace fossil fuel electricity generation.

We're going to need more than grid-scale batteries to electrify trucks, ships, and long-distance airplanes. PaulDavisThe1st is right about that! Solar-powered fuel production from CO₂ is one possibility.

Not for trucks but probably ships and planes.

Planes are unlike other sorts of transportation in that their energy consumption is pretty closely proportional to their weight, because they are constantly spending energy throwing air downward to support their weight, so the low energy densities of rechargeable batteries are very unappealing for long-distance flight. Plausible alternatives include airships, ultra-low-stall-speed planes like gliders and Burt Rutan's Voyager, aluminum-air batteries, and synfuel. Of course, short-distance planes are already going electric with Joby.

Ships, we'll see. Most shipping ships are container ships (as opposed to, say, tankers, cruse ships, or ship shipping ships shipping shipping ships), and those are already slow enough that a substantial part of world trade is by airplane now, because inventory on a container ship is inventory you can't sell yet, or at least can't deliver yet. You could imagine a future where container ships are partly powered by onboard sails and partly powered by giant lightweight solar farms towed behind them on hydrofoils, but I don't think we're going to see container ships powered by lithium-ion batteries. Aluminum-air, maybe.

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